Recrystallization Flashcards
Esterification
a type of condensation reaction that results in an ester
Condensation Reaction (2)
- a reaction in which two molecules combine to form a single molecule
- water is usually removed
What functional group does trimyristin contain?
ester
Extraction
the transfer of a solute from one phase to another
Soild-Liquid Extraction
start from a solid mixture, extract with a solvent
Filtration
the separation of a solid from a liquid by passing the solution through a medium through which only the liquid can pass
Why was diethyl ether used as the solvent for extraction? (2)
- esters and ethers have similar polarity
- trimyristin is an ester and diethyl ether is an ether
Polar Covalent Bond
a covalent bond with greater electron density around one of the two atoms
Recrystallization
a technique for the purification of a solid contaminated with relatively small amounts of solid impurities
What must be done to recrystallize? (3)
1) dissolve the impure solid in a suitable solvent
2) let only the pure solid compound crystallize while the impurities remain dissolved in the mother liquor
3) Vacuum filter to collect pure solid compound
How do you choose a suitable solvent for recrystallization? (3)
1) Compound should be fairly insoluble in room temperature solvent
2) Compound should dissolve completely in the solvent when heated
3) Pure compound should crystallize out when the solution is cooled on ice
How do you remove insoluble impurities? (2)
- dissolve them in the solvent
- filter off the impurities
How do you remove colored impurities? (2)
- add Norit
- perform hot filtration
Norit
activated charcoal which has a large surface area on which colored compounds are adsorbed
How do you remove soluble impurities?
recrystallization
Why do the impurities not crystallize out when the solution is cooled? (3)
- the solution is concentrated with respect to the target compound but dilute with respect to the impurities
- decreasing the temperature of the solution causes the solubility of the target and impurities to decrease
- the target compound crystallizes before the impurities because there is a greater concentration
